Topic Overview
What is Tay-Sachs disease?
Tay-Sachs is a rare
disease that is passed down through some families. A person with Tay-Sachs has changed (mutated) genes that don't make any or enough of an enzyme called hexosaminidase A (hex A). Hex A breaks down fatty compounds. Without it, fatty compounds build up in the nerve cells of the brain and cause damage.
There are two forms of Tay-Sachs:
- The most common form develops soon after a
baby is born. It causes death early in childhood.
- Late-onset Tay-Sachs can start between
puberty and the mid-30s. How long a person lives
depends on how severe the symptoms are. People may live as long as someone who
doesn't have Tay-Sachs disease. Late-onset Tay-Sachs is very rare.
What causes Tay-Sachs disease?
Tay-Sachs can occur
when parents pass on a changed gene to their child.
- If a baby gets the changed gene from both parents, he
or she will get the disease.
- If the baby gets the changed gene from only
one parent, he or she will be a
carrier. This means that the child will have one
gene that produces hex A and one that doesn't. The child's body makes enough hex A so that he or she doesn't get the disease. But the child can
pass the changed gene on to his or her children.
In late-onset Tay-Sachs (LOTS), the body
makes a small amount of hex A. People with LOTS inherit the late-onset hex A
gene change from one or both parents.
The changed gene that causes Tay-Sachs disease is more commonly found in people of Ashkenazi Jewish
descent. About 1 out of 30 people in this population is a carrier of the
disease.footnote 1 People of
French-Canadian descent from the East Saint Lawrence River Valley of Quebec and
people of Cajun descent in Louisiana are also more likely than others to carry the changed gene.
What are the symptoms?
A child with Tay-Sachs
disease looks healthy at birth. But when the child is:
- 3 to 6 months of age,
you may notice that the child makes less eye contact and has a hard time
focusing his or her eyes on things. A doctor may see a red spot on the child's
retina.
- 6 to 10 months of age, you may notice that the child is not as alert and playful as he
or she had been. It might be hard for the child to sit up or roll over. You
also may notice that the child does not see or hear well.
- 10 months and older, the disease gets worse quickly. The
child may have
seizures, have an intellectual disability, lose his or her vision, and not be able to
move.
Children with Tay-Sachs rarely live beyond 4 years of age.
In late-onset Tay-Sachs (LOTS), early symptoms such as
clumsiness or mood changes may be minor or seem "normal" and go unnoticed.
Later symptoms may include muscle weakness and twitching, slurred speech, and
trouble thinking and reasoning. The symptoms depend on how much hex A the body
makes.
How is Tay-Sachs disease diagnosed?
If you or your
doctor thinks that your child has Tay-Sachs disease, your doctor will do a physical
exam and a blood test to check the level of hex A. A genetic test may be needed
to be sure the disease is Tay-Sachs.
How is it treated?
The focus of treatment for
Tay-Sachs disease is to control symptoms and make your child as comfortable as
possible. There is no cure. It may be helpful to seek counseling or find
support from others who are going through the same thing you are.
If you have late-onset Tay-Sachs disease (LOTS), treatment also
focuses on controlling symptoms. The treatment you receive, such as medicine
for
depression, depends on the symptoms you have.
It may be overwhelming to learn that your child has Tay-Sachs. It's
important that you care for yourself as well as your child. Talk to your doctor
about:
- Your concerns and the help you'll need for
your child.
- A support group in your area.
- Family
counseling to help each member cope with the disease.
As the disease gets worse, your child will need more care.
Encourage your child to be as active as possible for as long as possible. Give
your child your love and affection.
You may not be able to care
for your child without help. Talk with your doctor about groups that can help
you.
Should you get tested?
If you
are thinking about having a child, the American College of Obstetricians and
Gynecologists (ACOG) recommends that:footnote 2
- Both you and your partner get a screening test if you are both of Ashkenazi Jewish, French-Canadian, or Cajun descent
or have a
family history of the disease. If both of you test
positive as carriers,
genetic counseling may help you with making
choices.
- You or your partner get a screening test if
either of you is of Ashkenazi Jewish, French-Canadian, or Cajun descent or has
a family history of the disease. If one of you tests positive for being a
carrier, the other partner should be tested.
Carriers of the Tay-Sachs
gene changes can pass the changed gene to their children even though the carriers don't have the
disease. If both you and your partner are carriers, there is a 1-out-of-4 chance
(25%) that any child you have will have Tay-Sachs disease.